Wednesday  |  Conference Center A  |  10:50 AM–11:10 AM

#13424, In-situ, Nanoscale Fracture Toughness Measurements of Single-crystal Silicon

Thin film adhesion is paramount to the reliability of a number of technologies, most notably in the microelectronics and microelectromechanical systems industries. In theory, films are designed to adhere to the underlying substrate, but in reality, sometimes exhibit fracture, delamination, and buckling due to residual stress and stress gradients. These failure modes often initiate by brittle fracture at the interface, suggesting that adhesion is partially dictated by a fracture resistance parameter such as toughness. Historically, toughness has been measured via ex-situ methods including scratch, indentation, bulge, and stressed overlayer tests. More recently, toughness has been quantified in-situ in a scanning electron microscope to both visualize the fracture path and extract multiple values per specimen; the test geometries and loading conditions have included cantilever beam bending, clamped beam bending, double cantilever beam (DCB) compression, micropillar splitting, and DCB wedging. A recent case study on silicon revealed that the first four in-situ methods resulted in similar plain-strain fracture toughness values for Si(100) and highlighted the advantages and limitations of each of the geometries. In this work, we expand the silicon case study to include the fifth in-situ geometry, thus allowing for a systematic investigation of the fabrication, testing, and modeling parameters necessary for in-situ, nanoscale toughness values via the DCB wedging method. Moreover, the work extends the previous case study on silicon in three major ways: (1) First, DCB measurements on three different Si orientations enables a quantitative assessment of the toughness resolution, (2) Second, instrumented indentation measurements on the same orientations provides a quantitative assessment of the toughness accuracy, and (3) Third, the combination of the two methods affords a quantitative means to detect slow crack growth in Si. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

Frank DelRio   Sandia National Laboratories
Scott Grutzik   Sandia National Laboratories
William Mook   Sandia National Laboratories
Sara Dickens   Sandia National Laboratories
Brad Boyce   Sandia National Laboratories
Eric Hintsala   Bruker Nano Surfaces
Douglas Stauffer   Bruker Nano Surfaces
Robert Cook   Independent Scientist